For this purpose, two types of s-protected thiomers, polyacrylic acid-cysteine-mercaptonicotinic acid (PAA-Cys-MNA) and polyacrylic acid-cysteine-N-acetyl cysteine (PAA-Cys-NAC), were synthesized and characterized by Fourier-transform infrared spectroscopy (FT-IR) and the quantification of attached disulfide ligands. The viscosity of both products was measured in the presence of NAC and mucus. Both thiomers were also evaluated regarding swelling behavior, tensile studies and retention time on the porcine intestinal mucosa. The FT-IR spectra confirmed the successful attachment of Cys-MNA and Cys-NAC ligands to PAA. The number of attached sulfhydryl groups was in the range of 660–683 µmol/g. The viscosity of both s-protected thiomers increased due to the addition of increasing amounts of NAC. The viscosity of the mucus increased in the presence of 1% PAA-Cys-MNA and PAA-Cys-NAC 5.6- and 10.9-fold, respectively, in comparison to only 1% PAA. Both s-protected thiomers showed higher water uptake than unmodified PAA. The maximum detachment force (MDF) and the total work of adhesion (TWA) increased in the case of PAA-Cys-MNA up to 1.4- and 1.6-fold and up to 2.4- and 2.8-fold in the case of PAA-Cys-NAC. The retention of PAA, PAA-Cys-MNA, and PAA-Cys-NAC on porcine intestinal mucosa was 25%, 49%, and 76% within 3 h, respectively. The results of this study provide evidence that less reactive s-protected thiomers exhibit higher mucoadhesive properties than highly reactive s-protected thiomers.As less reactive  For this purpose, a novel comparatively less reactive ligand cysteine-N-acetyl cysteine (Cys-NAC) was synthesized and attached to a polyacrylic acid (PAA) backbone. For comparison reasons, a highly reactive polyacrylic acid-cysteine-mercaptonicotinic acid (PAA-Cys-MNA) conjugate was prepared as its mucoadhesive properties are already reported in the literature [s-protected thiomers PAA-Cys-NAC and PAA-Cys-MNA were evaluated via rheological investigations, tensile studies, and mucoadhesion studies on the freshly excised porcine intestinal mucosa. Furthermore, the diffusion behavior of both thiomers in mucus was determined.Since mucoadhesive polymers entered the pharmaceutical arena in the early 1980s , extensith mucus . There aoperties ,12,13. Toperties . In addioperties . Even inoperties . Accorditerature . Both s-l-cysteine ≥ 98%, Dowex® 1 × 4 chloride form (100–200 mesh), 5,5′-dithiobis (2-nitrobenzoic acid) , sodium borohydride ≥ 98%, N-acetyl-l-cysteine ≥ 99%, Triethylamine ≥ 99%, and all other salts and solvents were purchased from Sigma Aldrich, Vienna, Austria. Acetonitrile  was obtained from Donauchemie GmbH, Vienna, Austria. The porcine small intestine was kindly donated by a local slaughter house.Poly (acrylic acid) (PAA) 450 kDa, dichloromethane (DCM) , dimethylformamide (DMF) , dimethyl sulfoxide (DMSO) , 2-mercaptonicotinicacid (MNA), l-cysteine to Cys–MNA. Briefly, 2 g of MNA was dispersed in 80 mL of demineralized water by ultrasonication for 10 min. Afterward, the pH was adjusted to pH 8 with 5 M NaOH obtaining a clear, yellow solution. In order to oxidize MNA, 2.5 mL of hydrogen peroxide (30% v/v) was added and stirred for 10 min until the solution became colorless. The pH was maintained during the reaction at pH 8–9. Following that, a solution containing 1 g of l-cysteine in 40 mL of demineralized water was adjusted to pH 8 and added drop-wise to the reaction mixture within 1 h. The pH was maintained during the reaction at pH 8.5–9.5 and a slightly yellow clear solution was obtained. Thin-layer chromatography (TLC) was used to verify that Cys–MNA was successfully formed. The stationary phase was silica gel with a fluorescent indicator coated on aluminum foils and a mixture of butanol:acetic acid:water (4:1:1) was used as the mobile phase. The plates were analyzed under black light (UV254) and subsequently sprayed with a ninhydrin solution (0.3% m/v in ethanol).The ligand (Cys–MNA) was synthesized in a two-step reaction. 2-Mercaptonicotinic acid (MNA) was first oxidized to the corresponding MNA-dimer with hydrogen peroxide according to a method described previously . The obtl-cysteine from the reaction mixture, two purification steps were performed. The pH of the slightly yellow solution was decreased to pH 7.5 to precipitate l-cystine since it is poorly soluble in aqueous media of pH 2–8 [l-cysteine is uncharged, whereas MNA, MNA-dimer and Cys–MNA are mainly negatively charged. Therefore, the column was packed with 30 g of anionic exchange resin , loaded with 250 mL of a 2 M NaCl solution, and washed with 250 mL of demineralized water. Afterward, the filtrate was added to the column and was washed two times with 250 mL of demineralized water in order to remove l-cysteine. The bound compounds were released by adding three times 250 mL of a 2 M NaCl solution and the collected eluent was reduced to 200 mL with a rotary evaporator. The solution was then frozen at −80 °C and lyophilized using a rotary vacuum evaporator . In order to eliminate unbound f pH 2–8 . The prel-Cysteine (605.8 mg) was dissolved in 20 mL of deionized water and its pH was adjusted to 8.2. NAC (815.975 mg) was dissolved in 20 mL of deionized water and its pH was adjusted to 8.2. Afterward, both solutions were mixed. A total of 0.567 mL of hydrogen peroxide (30% v/v) was then added to the mixture while maintaining pH at 8.5 to 9.5 with 5 M NaOH. The solution was continuously stirred for 2 h at room temperature. Thin-layer chromatography (TLC) was used to verify the formation of Cys-NAC in the same way as described for Cys-MNA. The pH of the solution was decreased to pH 7.5 to precipitate l-cysteine and cysteine dimer. The precipitates were filtered out and the obtained filtrate was then freeze-dried at −80 °C.v/v). Precipitates were separated by filtration and Cys-NAC was obtained from the filtrate by evaporating the solvent under vacuum. The structure of the Cys-NAC disulfide was further characterized by 1H NMR spectroscopy.In order to separate the remaining impurities from the product, the lyophilized product was dissolved in a mixture of acetonitrile and water (3:2 v/v) with 0.1% (v/v) formic acid at the concentration of 1 µg/mL. Mass spectral studies were performed in positive electrospray ionization (ESI) mode in the mass to charge ratio (m/z) range of 200–300 to determine molecular mass. In order to obtain clear mass spectra without any background noise, samples were directly infused into the mass spectrometer using a syringe pump at a flow rate of 2 µL/min.The molecular mass of Cys-NAC was determined using LC–MS according to our previously used method with minor modification . Mass spPAA anhydride was prepared by adapting a method previously described . For thi® cellulose membranes, Carl Roth GmbH & Co. KG, Karlsruhe, Germany (molecular weight cut-off (MWCO) 3.5 kDa) for 3 days. The dialysis solution was changed every 8 h. After 3 days, the dialyzed product was freeze-dried at −80 °C. Finally, the product was characterized by FT-IR.PAA anhydride (142 mg) was dissolved in 10 mL of DMF by stirring at 80 °C. Ligand Cys-MNA (822 mg) was dissolved in 10 mL of DMSO. The precipitates were separated by filtration. In the clear filtrate, triethylamine (278 µL) was added and stirred for a further 15 min. After this, the ligand solution was added to anhydride solution and left for stirring for 24 h at 80 °C. The usage of triethylamine was required to prevent the protonation of amine groups. The product was purified by dialysis against water at 10 °C in dark using Nadir® cellulose membranes, Carl Roth GmbH & Co. KG, Karlsruhe, Germany (molecular weight cut-off (MWCO) 3.5 kDa) for 3 days. The dialysis solution was changed every 8 h. After 3 days, the dialyzed product was freeze-dried at −80 °C. Finally, the product was characterized by FT-IR.PAA anhydride (142 mg) was dissolved in 10 mL of DMF by stirring at 80 °C. Cys-NAC (282 mg) was also dissolved in 10 mL of DMF and triethylamine (278 µL) was added. After 15 min, the ligand solution was added to anhydride solution and left for stirring for 24 h at 80 °C. The product was purified by dialysis against water at 10 °C in dark using Nadir2O was used as solvent and TMS as an internal standard.All FT-IR spectra were recorded on a Bruker ALPHA FT-IR apparatus equipped with a Platinum ATR  module. NMR spectra were recorded on a “Mars” 400 MHz Avance 4 Neo spectrometer, from Bruker Corporation . Ds-protected thiolated PAA conjugate was dissolved in 250 μL of Ellman’s buffer and 500 μL of Ellman’s reagent  3 mg/10 mL of Ellman’s buffer) were added to each sample and were kept for incubation in the dark for 2 h. Thereafter, 100 μL aliquots were transferred to a 96-well plate, and absorption was measured at 450 nm using a microplate reader . The amount of free thiol groups was then calculated using an already established calibration curve of l-cysteine under the same conditions. The degree of s-protection was determined by quantifying the amount of disulfide bonds. For this purpose, the above described procedure was followed after the reduction of disulfide bonds with sodium borohydride (NaBH4). The experiments were performed in triplicate.The thiolated products were analyzed for functional groups using Ellman’s test and disulfide bond test . For Ells-protected thiolated PAA conjugates was determined using the resazurin assay according to a previously described method [v/v) fetal calf serum (FCS). Cells were incubated for 14 days at 37 °C under 5% CO2 and a 95% relative humidity environment. During the incubation period, the medium was replaced every 48 h. Test solutions were prepared in the concentrations of 0.5%, 0.25% and 0.1% m/v in 25 mM HEPES buffered saline (HBS) pH 7.4. For the experiment, cells were washed twice with preheated HBS at 37 °C. Test solutions, positive control (HBS), and negative control (1% v/v TritonTM X-100) were added in triplicate to the cell culture plate in the volume of 0.5 mL/well and incubated at 37 °C in a 5% CO2 and 95% relative humidity environment for 4 h. After incubation, test solutions were removed and cells were washed twice with preheated HBS pH 7.4. An aliquot of 0.25 mL of 2.2 mM resazurin solution was added to each well and the cells were incubated again under the same conditions for 3 h. Afterward, the fluorescence of the supernatant from each well was measured at 540 nm excitation wavelength and 590 nm emission wavelength.The cytotoxic potential of unmodified and d method . BrieflyCell viability was calculated by the equation:s-protected thiolated PAA conjugates as described previously by our research group [m/v) solutions of each polymer in 50 mM phosphate buffer pH 6.8 were incubated with increasing concentrations of NAC 0.1, 0.5 and 1.0% (m/v) at 37 °C for 30 min. Unmodified PAA with the same concentration of NAC served as a control. The results were expressed as dynamic viscosity (η) increase with increasing NAC concentration for each sample. Each experiment was performed in triplicate.Rheological investigations were performed to determine the viscoelasticity of ch group . Experimm/v solution of each s-protected thiomer in a 2:1 ratio. The mixtures were incubated at 37 °C and viscosity was measured at pre-determined time points. Mucus mixed with 50 mM phosphate buffer pH 6.8 in the same ratio served as a control. The results were expressed as dynamic viscosity (η) increase with time. Each experiment was performed in triplicate.Moreover, porcine intestinal mucus was collected and purified as described by Iglesias et al.  and alsos-protected thiomers was determined by a method as previously described [s-protected thiolated PAA conjugates were prepared. For the preparation of disks, 30 mg of each product was compressed by a single punch eccentric press at 11 KN  with constant compaction pressure. The test disks were fixed on the clips and weighed. Afterward, the clips were immersed in 50 mM phosphate buffer pH 6.8. At predetermined time points, the clips with swollen test disks were removed from the buffer and weighed after gently removing excess water from the surface. The amount of water uptake at each time point was determined by the following equation: t is the disk weight at the specific time point and W0 is the initial disk weight.The swelling behavior of unmodified and both escribed . For this-protected thiolated PAA conjugates by a texture analyzer  following a previously described method with minor modifications [s-protected thiolated PAA conjugates were prepared as described above for determining the swelling behavior. The intestine was cut into small pieces of approximately 16 cm2 diameters and fixed between two acrylic glass disks of the texture analyzer. The test disks were fixed on the lower side of the 10 mm cylindrical probe adapter with adhesive tape. During the experiment, the probe adapter with a speed of 0.5 mm/s was lowered to the mucosa, and a force of 0.5 N was applied for a contact time of 15 min. Moreover, test speed was kept constant 0.1 mm/s. Subsequently, the probe adapter was moved up with a withdrawal speed of 0.1 mm/s until the adhesive bond between mucosa and test disk failed. Data analysis was carried out using Exponent software.Tensile studies were performed using porcine intestinal mucosa to evaluate the adhesive force of unmodified and ications . In thiss-protected thiolated PAA conjugates were labeled with fluoresceinamine according to a method described previously by Imam et al. [s-protected thiolated PAA-conjugate. Afterward, 20 mg of fluoresceinamine dissolved in 2 mL of 1 M NaOH was added to each solution, and the reactions were allowed to proceed for 3 h at room temperature at pH 5. The reaction mixtures were then dialyzed first against 0.2 mM HCl to remove unbound fluoresceinamine, then against the same medium with 1% m/v NaCl two times and finally against demineralized water. After dialysis, the solutions were freeze-dried  and stored at 4 °C until further use. Unmodified and m et al. . In bries-protected thiolated PAA conjugates on intestinal mucosal membranes, in vitro mucoadhesion studies were performed as previously described by our research group [2. Each piece of mucosa was mounted on a 50 mL half-cut falcon tube adjusted at an angle of 45° in an incubator maintained at 100% relative humidity and 37 °C. In the following, 20 mg of fluoresceinamine-labeled samples were separately placed on each mucosa and incubated for 10 min to fully adsorb on the mucosal surface. Afterward, each mucosa was continuously rinsed with the 50 mM phosphate buffer pH 6.8 at the flow rate of 1mL/min using a peristaltic pump. A total of 30 mL of phosphate buffer fractions flowing down the mucosa were collected at the time points of 0.5, 1, 1.5, 2, 2.5, and 3 h. In parallel, each 100% reference sample was prepared by rinsing the intestinal mucosa without any adsorbed sample using phosphate buffer and then dissolving each polymer sample in the collected buffer in a concentration of 0.67 mg/mL. All test and reference samples were centrifuged at 13,400 rpm for 5 min at room temperature and fluorescence intensity measurements were taken at an exciting wavelength of 485 nm and an emission wavelength of 535 nm. The percentage mucoadhesion of samples at each time point was calculated by the following equation:To evaluate the mucoadhesive properties of ch group . Freshlys-protected thiolated polymers across purified porcine intestinal mucus, the rotating tube method was applied as described previously [s-protected thiolated polymers were hydrated in 50 mM phosphate buffer pH 6.8 at a concentration of 1% m/v. Each solution (20 µL) was added to the open end of the mucus-filled tube and closed with an end cap. After 24 h of incubation time, the tubes were frozen at −80 °C. Afterward, tubes were cut into 3 mm slices and mixed with 200 µL phosphate buffer for 30 min in small tubes and centrifuged for 5 min at 13,400 rpm. The supernatant (100 μL) from each sample was added to 96-well black plates, and fluorescence intensities were measured at an excitation wavelength of 485nm and an emission wavelength of 535 nm with a microplate reader . Silicon tubes containing mucus without samples served as the negative control. Fluorescence of 20 µL of each test solution mixed with a slice of negative control silicon tube and 200 µL of phosphate buffer served as 100% reference control. The percentage mucus penetration of each sample in various segments was calculated based on the relevant 100% reference fluorescence value.To investigate the diffusion of the two eviously . In briep < 0.05 as the minimal level of significance.All experiments were performed in triplicate. Data were analyzed by GraphPad Prism 5 . All data were represented as mean ± SD. Statistical comparisons were made using one-way ANOVA and two-way Bonferroni multiple comparisons test and s-protected thiomers regarding their mucoadhesive properties. PAA with the low molecular mass of 2 kDa was shown to permeate, to a considerable extent, the mucus gel layer and, to some extent, even the underlying tissue. To exclude a systemic uptake of the mucoadhesive polymer, PAA with the medium molecular mass of 450 kDa that can permeate to some extent the mucus gel layer but not the underlying tissue was chosen [s-protected thiomers, the highly reactive MNA with a thiol pKa 1.87, and the less reactive NAC with a thiol pKa 9.7 were compared within this study. The first step to synthesize s-protected thiolated PAA conjugates was the generation and purification of the s-protected thiol ligands Cys-MNA and Cys-NAC, as shown in This study was based on a comparison of highly reactive and less reactive s chosen . As the l-cysteine was confirmed by thin-layer chromatography  of 283.0 representing the protonated form of Cys-NAC that is very close to the theoretically determined molecular mass of non-protonated Cys-NAC disulfide .For further evaluation, the molecular mass of Cys-NAC was determined by LC–MS with positive ESI mode. The mass spectrum as illustrated in s-protected ligands were covalently attached to PAA via amide bond formation using a novel method. For this purpose, PAA has converted to PAA anhydride as anhydride form is considered highly reactive. In the next step, PAA-anhydride was attached with each thiol ligand without the use of any catalyst. Following dialysis and lyophilization, both thiolated polymers were obtained as light brown fibrous materials. PAA was subjected to the same synthesis process but, without the addition of the respective ligand, served as a control and was obtained as white fibrous material. The chemical synthesis of PAA-anhydride and both thiolated PAA products is illustrated in Both −1, as shown in The structure of PAA anhydride was confirmed by FT-IR spectroscopy by the presence of the two anhydride C=O stretch bands at 1799 and 1750 cm−1 indicate the NH stretch of the amide bond in PAA-Cys-MNA and PAA-Cys-NAC, respectively.Final products were characterized by FT-IR spectra, as illustrated in s-protected thiolated PAA conjugate, as well as after the reduction of disulfide bonds, was determined. The results are depicted in Furthermore, the amount of free thiols on each s-protected thiolated PAA conjugates, Caco-2 cells were incubated with three different concentrations of each sample for 4 h. The results of the cytotoxicity studies are illustrated in m/v concentration. One possible explanation could be that PAA can form complexes with endogenous Ca2+ from intestinal epithelial cells, which might weaken the cellular barrier, leading to cell damage. This complexation depends on the availability of carboxylic groups. In the case of s-protected thiolated PAA, some of the carboxylic groups are not available anymore as they have been transformed to amide bonds with thiol-bearing ligands. As a consequence, their interaction with Ca2+ is reduced, resulting in lower toxicity. Unmodified PAA may deprive the cells of Ca2+ by forming complexes with extracellular Ca2+. This effect might weaken the cellular barrier, leading to cell death [m/v concentration, whereas, at the same concentration, PAA-Cys-NAC showed 86% cell viability. Comparatively higher toxicity of PAA-Cys-MNA can be attributed to the s-protecting group MNA, whose adverse effects are not fully investigated yet. However, the result confirmed the advantage of using NAC for s-protection, as it is endogenous with a well-established safety profile.In order to evaluate the cytotoxic potential of unmodified and ll death . The cels-protected thiolated PAA conjugates without the addition of NAC were used as respective controls. As shown in s-protected thiol ligands in comparison to PAA-Cys-NAC.Rheological measurements are the common way to evaluate the mucoadhesive strength of thiomers as they reflect the degree of interaction between thiomers and thiol-bearing moieties. The solution of NAC in increasing concentration was used to determine the impact of thiol/disulfide exchange reaction on viscosity improvement. Unmodified PAA and s-protected thiolated PAA conjugates at different time points as shown in s-protected thiolated PAA conjugates effectively enhanced the viscosity of mucus within 3 h. Mucus viscosity was statistically (p < 0.05) higher (10.9-fold) with PAA-Cys-NAC as compared with PAA-Cys-MNA (5.6-fold). We can conclude that PAA-Cys-MNA strongly interacts with superficial thiol groups of mucus, hindering further mucus penetration, whereas PAA-Cys-NAC can deeply interpenetrate, resulting in more intensive interactions with mucus. It was observed that the viscosity of PAA-Cys-NAC was more efficiently enhanced in the presence of mucus than NAC. This difference can be explained by the higher extent of crosslinking due to disulfide exchange reactions taking place between cysteine-rich subdomains of mucins and deeply penetrated PAA-Cys-NAC. In contrast, in the presence of NAC exhibiting just one thiol group, disulfide/thiol exchange reactions do not occur so rapidly and efficiently. The mechanism of thiol/disulfide exchange reactions taking place within the mucus has been schematically represented in s-protected chitosan than the corresponding highly reactive thiomer [The viscosity of mucus was also measured after the addition of PAA and  thiomer .p < 0.05) swelling than both s-protected PAA conjugates. Both s-protected thiomers showed a constant increase in the water uptake for 2 h. A high water uptake favors the inter-diffusion process between the mucus layer and polymer resulting in stronger mucoadhesion [Mucoadhesive polymers are well known to absorb water from the underlying mucosal layer. As this process also has a substantial impact on mucoadhesion properties, water uptake studies were carried out with disks of unmodified PAA, PAA-Cys-MNA, and PAA-Cys-NAC. The results, as illustrated in adhesion . It alsoadhesion . s-protected thiolated PAA conjugates on intestinal mucosa as illustrated in p < 0.05) MDF (2.4-fold) and TWA (2.8-folds) as compared to unmodified PAA.Tensile studies were performed to evaluate the adhesive features of unmodified and s-protected thiolated PAA than unmodified PAA. These mucoadhesive properties are in accordance with previous findings, which strongly support the notion that a higher degree of thiolation improves mucoadhesion [Mucoadhesive properties were further evaluated by the flow-through method. The basic principle of this mucoadhesion test is the quantification of PAA conjugates detaching from the mucosa as a function of time . The resadhesion ,26. The s-protected thiomers showed similar swelling behavior, as shown in s-protected thiomer. Once in contact, PAA-Cys-MNA rapidly interacts with mucus based on disulfide exchange reactions that hinder their deep penetration into mucus, whereas the reactivity of PAA-Cys-NAC is not too high to hinder its deep interpenetration. Due to this deep interpenetration, it can also interact with the firm mucus layer adhering to the epithelial layer, which prevents its easy washout from the mucosal surface. Moreover, the protection of thiol groups in s-protected thiolated PAA conjugates does not only prevent early oxidation of thiols but also enhances mucosal contact time, whereby more active thiol groups are available for longer periods of intimate contact with the mucosal membrane in many different ways [Thiolated polymers get attached to the mucosa mainly via disulfide exchange reactions with cysteine-rich domains of the mucus layer. In addition to these disulfide exchange reactions, some weak electrostatic or van der Waals interactions may also be involved in mucoadhesion . As bothent ways . Thiolatent ways  and seves-protected thiolated PAA conjugates were applied to mucus-containing silicon tubes as the elongated mucus barrier model in order to investigate the diffusion ability of these compounds into deeper regions of the mucus gel layer. The results of this study are illustrated in s-protected thiomer, PAA-Cys-NAC, and provided a proof-of-concept that it is a greater mucoadhesive than the well-established, highly reactive s-protected thiomer PAA-Cys-MNA. The mucoadhesion of PAA-Cys-NAC was 3-fold higher on intestinal mucosa in comparison to unmodified PAA and about 1.6-fold higher than PAA-Cys-MNA. According to these results, the Cys-NAC ligand seems to be a promising tool for the design of less reactive but highly mucoadhesive s-protected thiomers.Mucoadhesion is a complex process that involves in the case of thiomers, non-covalent and covalent interactions . In this


Stvb-i, is known to have conferred sustained resistance to Rice stripe virus (RSV) despite global warming. Stvb-i protects plants from growth stunting caused by RSV. The underlying resistance mechanism is unclear. Here, Stvb-i showed stable RSV resistance for 20 years in laboratory experiments. This gene encodes a protein distinct from well-studied plant disease-resistance proteins. It has a domain homologous to the histidine kinase/heat-shock protein 90-like ATPase superfamily. Rice has three paralogous genes including Stvb-i. The genes are expressed mainly in meristematic tissues. In the initial period after viral inoculation, RSV multiplication enhanced Stvb-i, whereas Stvb-i suppressed RSV multiplication. Stvb-i silencing inhibited plant growth regardless of viral infection, and silencing of the other paralogous gene that located closely to Stvb-i caused morphological abnormalities. The results suggested that the Stvb-i and its paralogs are related to plant development; especially, Stvb-i supports meristem growth, resulting in plant growth stabilizing. Growth stunting in the Stvb-i–silenced plants was more severe under repetitive heat stress, suggesting that Stvb-i contributed to the attenuation of heat damage in plant development. The symptoms of RSV infection  were similar to those of heat damage, suggesting that RSV multiplication induces heat-like stress in meristematic cells. Our findings suggest that the mechanism of meristem growth protection conferred by Stvb-i allows plants to withstand both heat stress and RSV multiplication. The suppression of RSV multiplication by the Stvb-i function in meristems results in durable resistance.Disease resistance is affected by temperature. A rice gene,  Plants need to withstand abiotic and biotic stresses such as temperature fluctuations, water scarcity (drought), wind, excessive or insufficient light, and pathogens. Viral multiplication in plant meristems directly threatens plant survival because meristems are indispensable for plant growth and development. Plants have evolved sophisticated systems that allow them to avoid or reduce damage to meristems.Rice stripe virus (RSV), an RNA virus causative of rice stripe disease, invades plants when they are sucked by the small brown planthopper  and greatly damages rice production, mainly in temperate East Asia, the world leading rice production area (1). Infection at the seedling stage causes severe leaf and systemic symptoms, resulting in plant death  cultivars Tsukinohikari, Asanohikari, and Musashikogane are RSV-resistant descendants of a resistant cultivar St No. 1 into which the RSV resistance gene Stvb-i of the indica rice cultivar Modan was introgressed; all three cultivars have the Stvb-i gene  at the F7 generation developed from a cross between Tsukinohikari and Koganebare were used to delimit the Stvb-i region; among them, RIL3245 was resistant and RIL484 was susceptible . Each plant with chlorosis  was counRice stripe virus inoculation for tissue staining and RNA analysis was performed as follows: rice seedlings at the 1.0–1.5-leaf stage were exposed to 10 viruliferous SBPHs per plant at 25–27°C in a growth chamber, and the insects were removed after 24 h. Non-viruliferous SBPHs were used for mock-inoculation of control plants. Plants were kept in the growth chamber until RNA preparation.4) and antibody against RSV , and were observed under a digital microscope VHX-5000 (Keyence5) using without imaging modification.Paraffin sections were prepared from 3–5 mm pieces of the bases of rice seedlings. Seedling bases at 5–10 days after RSV inoculation were sampled. Sections were stained with a Vectastain ABC-AP kit (Vector Laboratories6) were used for DNA sequencing. The Stvb-i genomic region sequences of St No. 1 and Nipponbare provided by the Rice Genome Project  were used for marker development and sequence comparison. Candidate Stvb-i ORFs were predicted and annotated with the Rice Genome Automated Annotation System .An ABI310 genetic analyzer and a BigDye Terminator Cycle Sequencing Kit version 3.1 . Genomic DNA of St No. 1 was purified as described elsewhere . A transformation-competent artificial chromosome (TAC) library was constructed in BamHI-digested pYLTAC7 as described elsewhere (Agrobacterium tumefaciens LBA4404 (Invitrogen11). Plants were transformed with A. tumefaciens as described elsewhere (LC157868) evaluated for RSV resistance in the complementation test were derived from RIL484 , and Yuukara .The DNA of the t0014J19  was purilsewhere , partiallsewhere . Clones lsewhere . TransgeST07i (the candidate for Stvb-i), an internal fragment, NK5 trigger  from 3–5-mm pieces of the bases of seedlings  Core Set (Takara-Bio12). Full-length cDNA was generated using an RNA LA PCR Kit (Takara-Bio), cloned using a Mighty TA-Cloning Kit (Takara-Bio), and sequenced. The transcripts of Stvb-i paralogous genes were identified on the basis of database information, amplified from suitable tissues as above and sequenced.For D31879.1 (RdRp on RNA1), D13176.1 (P2 and Pc2 on RNA2), D01094.1 (NS3 and CP on RNA3), and D01039.1 (P4 and Pc4 on RNA4). Rice glyceraldehyde 3-phosphate dehydrogenase  was used as an internal reference gene.All primers and the sizes of the amplified fragments are listed in Stvb-i expression in RSV-infected plants, seedlings were sampled every day at noon. Total RNA was prepared from six seedlings inoculated with or without RSV. Quantitative RT-PCR was conducted on an ABI7500 Real-time PCR System (Applied Biosystems) using a SYBR PrimeScript RT-PCR Kit (Takara-Bio). Stvb-i expression levels were determined by the standard curve method; rice OsGAPDH (see above) was used as an internal reference gene. To compare gene expression in heated and non-heated rice plants, total RNA was prepared from four seedlings per treatment. Quantitative RT-PCR was conducted on a Roche Lightcycler 480 Real-Time PCR system (Nippon Genetics13) using Thunderbird SYBR qPCR Mix (Toyobo14). The results were analyzed by the ΔΔCT method; rice OsGAPDH was used as an internal reference gene. The mean relative expression levels and the SEM (n = 3) were calculated using the statistical package BellCurve for Excel . A Tukey–Kramer multiple comparison test was used for data analysis.To measure Stvb-i–silenced lines (St507 and St509) and three Stvb-i–complemented lines  were used for plant phenotyping as follows.Two Stvb-i–silenced lines  were used. Seedlings were inoculated with RSV at 1.5-leaf stage (6 days after germination) and the aboveground height was measured at 36 days after germination. Susceptible Nipponbare was used as reference.To investigate the relationship between plant growth and RSV inoculation, St No. 1 and Stvb-i–silenced and -complemented lines of St No. 1 and Yuukara  were used. Non-infected plants were grown under normal growth conditions from May to August in Tsukuba, Japan. The tillers were counted 54 days after germination (vegetative stage) and 84 days after germination (heading stage).For tiller counting, Stvb-i in heat stress, Stvb-i–silenced lines and St No. 1 were used. The aboveground height of 20 RSV-uninfected plants was measured from day 0 (start) to day 10. Leaf stage was measured from day 0 to day 11 with reference to To investigate the role of All data were analyzed by a one-way or two-way analysis of variance (ANOVA), and if necessary a Tukey–Kramer multiple comparison test.Stvb-i–silenced and -complemented plants were exposed at 35–37°C for 4 days at 1st-leaf stage (4 days after germination) and were grown in a plant growth chamber for 7 days and then in a glasshouse. Similar observations were performed three times. To investigate the role of Stvb-i in heat stress, 20 seedlings of each of the silenced lines and WT St No. 1 at the 1st-leaf stage were left untreated or were heat-treated at 38°C for 2 days once or three times, and then grown at 25°C  and 20°C  in a controlled plant growth chamber. The plant height and leaf stage were determined (see section “Plant Height and Tiller Number”).Healthy seeds with coats removed were surface-sterilized with sodium hypochlorite solution (2.5% effective chlorine concentration), washed several times with sterile distilled water, and soaked in sterile distilled water at 20°C for germination. Germinated seeds were planted in soil and seedlings were grown at 25°C  and 20°C  in a controlled plant growth chamber. Rice seedling growth declines above 35°C . For obsStvb-i–silenced lines and St No. 1 were used. Germinated seeds were placed on 0.4% gellan gum containing 1/5 Murashige–Skoog medium in a plastic box for plant tissue culture. The seedlings were heat treated at 38°C for 12 h at the 1.5-leaf stage. Meristematic tissues were sampled at 0, 6, 12, 18, 24, 36, 48, and 60 h from the start of heat treatment (at 09:00 h), and RNA preparation and analysis were performed as described above.For expression analysis, Stvb-i, the signals were strongest in the upper part of the developing leaves in the sheath, were weaker in the base part of the leaves, and were very weak in the meristem. These data suggest that, although RSV multiplies in young leaves, the increase in the number of virus particles is suppressed in the meristem of Tsukinohikari, i.e., Stvb-i–mediated resistance suppresses RSV propagation in meristematic tissue.In an RSV-resistant cultivar Tsukinohikari at 10 days after RSV inoculation, viral concentration at the seedling base is low and viral spread to the upper leaves is suppressed as compared to a susceptible cultivar Nipponbare . We usedWe evaluated the severity of RSV infection on the basis of leaf symptoms, mainly chlorosis (yellowing) and twisting , in fourStvb-i; in all resistant rice cultivars, it rarely exceeded 0.4  as candidates for Stvb-i , which is derived from an indica rice Kasalath and encodes an enzyme sulfotransferase  and complementary sense  increased more slowly in a resistant cultivar than in a susceptible cultivar  in the resistant cultivar than in the susceptible cultivar. Thus, although RSV is able to multiply in both resistant and susceptible rice cultivars, multiplication is slower in resistant rice. This result is consistent with the immunohistochemical observation   . In non-his time . HoweverStvb-i expression in the silenced lines derived from St No. 1, in which the effect of Stvb-i was slightly stronger than in Tsukinohikari  in Nipponbare , and was highly expressed in calluses, but not in elongated leaf blades . Non-inoculated mature plants of these lines also had fewer tillers , the tiller number was decreased significantly in all three lines at the heading stage, but not at the vegetative stage  than in mild summers at Sapporo in 2009 ; leaf drying, chlorosis and lamina joint bending were observed at both locations, and panicle malformation was observed at Tsukuba in the Stvb-i–silenced line (Stvb-i silencing on plant growth is particularly strong under heat stress.The ced line . We hypoStvb-i–silenced lines (St507 and St509) and the wild-type St No. 1 (Stvb-i–complemented lines (DY505 and DY508). In contrast to the Stvb-i–silenced lines, the complemented lines grew without stunting (Stvb-i on growth of heated seedlings.Heat treatment (4 days at 35–37°C at the 1st-leaf stage) promptly caused chlorosis on whole seedling and short crown root . Five daSt No. 1 . HoweverSt No. 1 . At 56 dSt No. 1 . The samstunting . The silStvb-i up to 3-leaf age   of N. benthamiana. NbHsp70 is associated with multiplication of Chinese wheat mosaic furovirus in N. benthamiana and affects leaf development (Heat shock proteins 70 (Hsp70s) are important in the thermal response , and areculation , and Os0°C 10 h) . Anotherelopment .Stvb-i expression level seemed to increase slightly in heated than in unheated plants and was about twice the level of unheated plants at 6 h; the expression levels became similar at later time points regardless of heat treatment , and function (contribution to recovery from heat stress and influence on plant development). Stvb-i may regulate heat-sensitive signaling cascades closely linked to meristem growth.Temperature above the optimum for growth impairs cell homeostasis , and plaHsp70 genes, Os03g60620, Os11g08470, and Os05g38530, has been suggested . A stable expression of Stvb-i  and thus preventing pathogen invasion and propagation, which results in selective pressure. The interaction between an NBS-LRR protein and pathogenic factor requires Hsp90 and is therefore temperature sensitive . RSV resf Stvb-i , 7, whicOur study has demonstrated that rice acquires sustainable dual tolerance to abiotic and biotic stresses through the stability of plant growth. In the context of global warming, exploration of genes involved in the metabolic and signaling systems that maintain meristem growth will be conducive to conferring multi-tolerance in plants. Improvement of developmental stability will help secure the productivity of crops under diverse environmental conditions.The datasets generated for this study are included in the article/YH-S and KH performed the experiments and analyzed the data. YH-S designed the experiments and wrote the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


There is limited information concerning the viral load of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in aerosols deposited on environmental surfaces and the effectiveness of infection prevention and control procedures on eliminating SARS-CoV-2 contamination in hospital settings. We examined the concentration of SARS-CoV-2 in aerosol samples and on environmental surfaces in a hospital designated for treating severe COVID-19 patients. Aerosol samples were collected by a microbial air sampler, and environmental surfaces were sampled using sterile premoistened swabs at multiple sites. Ninety surface swabs and 135 aerosol samples were collected. Only two swabs, sampled from the inside of a patient's mask, were positive for SARS-CoV-2 RNA. All other swabs and aerosol samples were negative for the virus. Our study indicated that strict implementation of infection prevention and control procedures was highly effective in eliminating aerosol and environmental borne SARS-CoV-2 RNA thereby reducing the risk of cross-infection in hospitals. Since the outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the end of 2019 in Wuhan, China, this severe infection has spread rapidly around the world . AccordiSARS-CoV-2 can spread via respiratory droplets, bodily fluids or contaminated surfaces . Of noteCurrently, a wide variety of aerosol sampling methods are in use and several other methods are in the developmental stage . HoweverThe study was performed from 20 February to 5 March 2020 at Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, which is a designated hospital for treating severe and critical COVID-19 patients diagnosed according to the Chinese management guidelines for COVID-19 (version 7.0) . Patientc. 5 cm2) were sampled with saline-moistened swabs after routine cleaning on three separate days. All samples were analysed in the BSL-2 laboratory by RT-PCR in accordance with the WHO protocol [Approximately 1 h after routine twice-daily cleaning of contact surfaces (using 500 mg/l sodium dichloroisocyanurate) and floors (using 1000 mg/l sodium dichloroisocyanurate) and after 4-time-daily air disinfection using a plasma air steriliser , aerosol samples were collected by an impingement air sampler . This instrument employs the positive potential of SLC-SiOH magnetic beads, which can enrich aerosol particles of diameter 0.03–0.5 μm containing negatively charged RNA viruses . In brieprotocol . A cycleA total of 90 environmental surface swabs was collected from 30 locations inside and outside the isolation wards . All, exConsistent with other respiratory acquired viral agents, the main transmission routes of SARS-CoV-2 are via respiratory droplets and close contact. A recent study demonstrated that viable SARS-CoV-2 could be detected in laboratory-generated aerosols up to 3 h post aerosolisation, and the viable virus was detectable up to 4 h on copper, 24 h on cardboard and 2–3 days on plastic and stainless steel . It is tet al. [In our study, SARS-CoV-2 RNA was not detected in any of 135 aerosol samples from different areas of a designated hospital for severe COVID-19 patients. This result is inconsistent with the findings of Liu et al. , who repet al. –19 also et al. , 21 repoet al. [Furthermore, with the exception of two samples from a COVID-19 patient's mask, all 90 environmental surfaces sampled were negative for SARS-CoV-2. Although viral RNA was detected by Ong et al.  on some et al.  and Italet al.  also teset al. , 24, 25 et al. , 25.clean, buffer and contaminated zones, with doctor and patient channels. The isolation ward should have negative pressure ventilation with 12 or more air changes per hour. (ii) Strict policies should be in place for environmental disinfection/cleaning and hand hygiene [Based on our evidence, we believe that the current disinfection measures used in our hospital setting are sufficient to eliminate, or reduce to undetectable levels, SARS-CoV-2 contamination. Since the end of January 2020, to date, our hospital has admitted more than 1600 patients and none of 3255 HCWs in the hospital has become infected. Nevertheless, the detection of viral RNA on the mask worn by the COVID-19 patient reminds us to remain cautious and vigilant during close contact with patients with strict adherence to hand hygiene. From our experience, we propose that the following measures are essential for achieving a safe hospital environment during the COVID-19 epidemic. (i) An isolation ward should be set up with ‘three zones and two channels’, namely,  hygiene . (iii) P hygiene .There are several limitations to this study. First, the volume of air sampled and the number of environmental surfaces swabbed represent only a small fraction of the whole; thus, some contaminated areas may have been missed. Second, a qualitative test of SARS-Co-2 RNA was used, and therefore we cannot rule out the presence of low concentration of virus below the detection threshold in these samples. Lastly, because viral culture was not performed, we are unable to confirm the presence of viable virus on the environmental surfaces sampled.In conclusion, our findings suggest that the current infection prevention control practices utilised in a designated COVID-19 hospital appear to be very effective in reducing and lowering the risk of SARS-CoV-2 transmission from aerosols and environmental surfaces to other patients and HCWs.


Background: Oximes are used in addition to atropine to treat organophosphate poisoning. However, the efficiency of oximes is still a matter of debate. In vitro experiments suggested than new oximes are more potent than the commercial oximes. However, the antidotal activity of new oximes has not been assessed in vivo. Methods: The aim of this work was to assess the safety and efficiency of new oximes compared to pralidoxime in a rat model of diethyl paraoxon-induced non-lethal respiratory toxicity. Results: Safety study of oximes showed no adverse effects on ventilation in rats. KO-33, KO-48, KO-74 oximes did not exhibit significant antidotal effect in vivo. In contrast, KO-27 and BI-6 showed evidence of antidotal activity by normalization of respiratory frequency and respiratory times. KO-27 became inefficient only during the last 30 min of the study. In contrast, pralidoxime demonstrated to be inefficient at 30 min post injection. Inversely, the antidotal activity of BI-6 occurred lately, within the last 90 min post injection. Conclusion: This study showed respiratory safety of new oximes. Regarding, the efficiency, KO-27 revealed to be a rapid acting antidote toward diethylparaoxon-induced respiratory toxicity, meanwhile BI-6 was a late-acting antidote. Simultaneous administration of these two oximes might result in a complete and prolonged antidotal efficiency. Organophosphates (OPs) are used daily around the world as pesticides. However, they remain a major health concern because of the large annual number of acute poisonings. Indeed, according to the data of the World Health Organization, there are more than 3 million of organophosphate intoxications annually and more than 220,000 deaths ,2.Respiratory failure is considered the primary cause of death in acute organophosphate poisoning ,4,5. StiThere has been a recent regain of interest in assessing the efficiency of new oximes, compared to older products, in reversing OPs toxicity ,13. OximWe developed a rat model to assess ventilatory effects induced by a non-lethal model of paraoxon toxicity using whole body plethysmography in awake animals ,18. NoteUsing PRX as a reference, the aim of this study was to compare the safety and the efficiency of a selection of new promising oximes  namely KTOT), expiratory time (TE), inspiratory time (TI), tidal volume (VT), and minute volume (VE) when comparing the control and oxime groups.Baseline values: There were no significant differences regarding to the temperature, the frequency (f), total time   exhibited urination, defecation, hypersalivation, and fasciculation. The mean core temperatures in the control group remained unchanged. After DEPO administration, the mean core temperatures decreased in the DEPO group and were significantly lower than the values observed for the control group from 30 min until the completion of the study (< 0.001) .As reported in p < 0.01) and demonstrated to be significantly higher at the end of the experiment (210 min) in comparison with the DEPO group (p < 0.001)  . HoweverTTOT and TE increased and plateaued 30 min after DEPO administration until the completion of the study (p < 0.001). The VT also increased significantly and plateaued 30 min after DEPO administration  but decreased at time 180 and 210 min. Conversely f decreased in the DEPO group and was significantly lower than the control group (p < 0.001). DEPO did not have any significant effect on TI and VE.Plethysmography: The administration of DEPO induced the rapid onset of significant alterations of the ventilatory parameters . In compTTOT between 15 and 30 min consequently to PRX administration (p < 0.05 or p < 0.01) and in TE between 5 and 45 min (p < 0.01 or p < 0.001). A significant increase in f could be observed between 5 and 45 min after PRX administration (p < 0.01 or p < 0.001). Regarding VT, a significant decrease was effectively recorded from 15 to 90 min after PRX administration . TE also showed a significant decrease from 15 to 180 min after KO-27 administration (p < 0.001), similarly to f which increased as well (p < 0.05 or p < 0.001). During this period of time, f returned within the normal range. KO-27 did not have any significant influence on VT, TI, and VE.In comparison with the DEPO group, the DEPO+KO-27 group showed a significant decrease in TTOT and TE between 60 and 180 min after BI-6 administration (p < 0.01 or p < 0.001). In parallel, data obtained showed a significant increase in f between 120 and 180 min after BI-6 administration (p < 0.001). During this period, TTOT, TE, and f returned to values within and above the normal range. Regarding VT, a significant decrease could be observed from 60 to 180 min after BI-6 administration (p < 0.001). During this period, VT returned in the normal range   and Decree of 20 October, 1987 (87-848/EEC) and approved by local ethic Committee under the number is P2.FB.164.10.Male Sprague-Dawley rats (250–300 g) were purchased from Janvier . All the animals were housed in a room with controlled environment , and maintained under a 12-h light/dark cycle. Animals had free access to food and tap water.50 as previously described in [Diethyl-paraoxon  was obtained from Sigma-Aldrich . Diethyl-paraoxon was diluted in dimethylsulfoxide (DMSO) so as to obtain a mother solution of 3.5 mg/ml. A daughter solution of paraoxon was prepared in saline (140 µg/mL), so as to inject doses equal to 50% of the LDribed in .®) was kindly provided by S.E.R.B laboratory . Pralidoxime was diluted in isotonic saline solution to obtain a 1.0 mg/mL mother solution, stored at −20 °C and stable for a maximum of 6 months. All doses were expressed as PRX cation and a correction factor of 1.7 between PRX and Contrathion® can be used [Pralidoxime (CAS number: 6735-59-7) methylsulfate  were synthesized in Czech Republic and were a gift of Pr. Kuca . Oximes were diluted in isotonic saline solution to obtain a 1.0 mg/mL mother solution, stored at −20 °C, and stable for a maximum of 6 months. PRX and new oximes, were 50 mg/Kg of oxime cation administered intra muscularly. The solutions were stored at +4°C for one-month maximum.All solutions of diethyl-paraoxon were prepared under fume hood using nitrile gloves, overall and goggles. Molar sodium carbonate solution was set under fume hood to neutralize immediately diethyl-paraoxon in the case of accidental spillage. Daily, after each experimental study, the same solution was used to decontaminate and clean up all materials and areas.The animals were clinically observed while plethysmography measurements were performed. The signs were noted and quantified according to De Candole et al. . ClinicaVentilatory parameters were recorded in a whole-body plethysmography by the barometric method described and validated in the rat by Bartlett and Tenney  with min2O, Northridge, CA, USA), connected to the animal and reference chambers. During each measurement, calibration was performed by one injection of 1 mL of air into the chamber and the ambient temperature was noted. The spirogram was recorded and stored on a computer with acquisition data card  using respiratory acquisition software  for off-line analysis. This technique was validated according criteria previously reported [The animals were placed in a rectangular Plexiglas chamber with a volume of 3 L connected to a reference chamber of the same size by a high-resistance leak to minimize the effect of pressure changes in the experimental room. The animal chamber was flushed continuously with moisturized air at a rate of 5 L/min. During recording periods, the inlet and outlet tubes were temporarily clamped and the pressure changes associated with each breath were recorded with a differential pressure transducer , inspiratory time (TI expressed in s), expiratory time (TE expressed in s) total respiratory time , the respiratory frequency (f expressed in bat/min), and the minute ventilation (VE = VT × f expressed in µL).The following parameters were measured: ambient temperature in the chamber, temperature of the animal, tidal volume  was inserted aseptically into the peritoneal cavity. The abdomen was closed with sutures and wound clips. The animals were allowed to recover for at least 7 days prior to experimentation ,20.Animals were randomly divided into seven groups . The control group received 0.5 mL sodium isotonic solution as solvent of diethyl-paraoxon followed by 0.5 mL sodium isotonic solution as solvent of oximes. The oxime groups received the solvent of diethyl-paraoxon (0.5 mL) followed by PRX, KO-27, KO-33, KO-48, KO-74, and BI-6 solutions using a similar dose to 50 mg/Kg, as stated in the method section. All oximes were administered intramuscularly in the upper of the tight muscle, 30 min after the solvent of diethyl-paraoxon. The first plethysmography measurement was performed after a period of accommodation of 30 min. Then, the rat was gently removed from the chamber for the subcutaneous injection of solvent of diethyl-paraoxon and replaced in the chamber for another session of respiratory recording. Ventilation was recorded 15 and 30 min after injection. Then, the animal was gently removed from the chamber for the intramuscular injection either solvent of oximes for control group, or oxime solutions for oxime groups. The rat was then replaced in the chamber and measurements were recorded at 35, 45, 50, 60, 75, 90, 120, 180, and 210 minAt the end of each experiment, rats were sacrificed with an overdose of pentobarbital.50 determined in our laboratory [Animals were randomly divided into eight groups . The control group received 0.5 mL sodium isotonic solution as solvent of diethyl-paraoxon followed by 0.5 mL sodium isotonic solution as solvent of oximes. The poisoned group received diethyl-paraoxon followed by the solvent of oximes. Diethyl-paraoxon was administered subcutaneously at a 0.215 mg/kg dose corresponding to 50% of the LDboratory . A previboratory . Therefop < 0.05 was considered significant.Results are expressed as mean +/− S.E.M (standard error of the mean). Graphs and statistical analysis were performed using Prism version 5.0, GraphPad Software . All tests were two-tailed, a The area under the curve (AUC) after drug injections until the completion of the study were calculated using the trapezoidal method .In the first study, we addressed whether the administration of oximes alone had any effects on the ventilation at rest. Accordingly, the effects of these treatments in rats were compared to the effects of the solvent (sodium isotonic solution) administered to animals using a two-way analysis of variance for repeated measurements. For each parameter, when a significant time*treatment interaction was found, this analysis was followed by multiple pair-wise comparisons.In the second study, the aim was to study the antidotal activity of the oximes toward diethyl-paraoxon-induced respiratory toxicity. Accordingly, the oxime groups were compared to the diethyl-paraoxon group while the solvent group allowed assessing the magnitude of the reversal of paraoxon-induced respiratory toxicity. Statistical analyses were made using a two-way analysis of variance for repeated measurements. For each parameter, when a significant time*treatment interaction was found, this analysis was followed by multiple pair-wise comparisons.


Graphene and its hybrids are being employed as potential materials in light-sensing devices due to their high optical and electronic properties. However, the absence of a bandgap in graphene limits the realization of devices with high performance. In this work, a boron-doped reduced graphene oxide (B-rGO) is proposed to overcome the above problems. Boron doping enhances the conductivity of graphene oxide and creates several defect sites during the reduction process, which can play a vital role in achieving high-sensing performance of light-sensing devices. Initially, the B-rGO is synthesized using a modified microwave-assisted hydrothermal method and later analyzed using standard FESEM, FTIR, XPS, Raman, and XRD techniques. The content of boron in doped rGO was found to be 6.51 at.%. The B-rGO showed a tunable optical bandgap from 2.91 to 3.05 eV in the visible spectrum with an electrical conductivity of 0.816 S/cm. The optical constants obtained from UV-Vis absorption spectra suggested an enhanced surface plasmon resonance (SPR) response for B-rGO in the theoretical study, which was further verified by experimental investigations. The B-rGO with tunable bandgap and enhanced SPR could open up the solution for future high-performance optoelectronic and sensing applications.  SPR is eratures . In numeeratures  gold naneratures  and graperatures .2 [Some novel materials such as graphene , reduced2  have bee2 . HoweverRecent studies have shown significant improvements in graphene properties by doping it with different heteroatoms such as Florine (F), Oxygen (O) , Nitroge2 bonded hexagonal structure of the carbon network induces P-type characteristics with an enhanced hole concentration and charged carrier’s mobility [In this work, we have investigated the plausibility of microwave-assisted hydrothermally grown boron-doped reduced graphene oxide (B-rGO) as a promising material to achieve desired properties. The reduction of GO using the microwave-assisted technique is favorable owing to its easy process-ability, short time requirement, high yield, non-requirement of hazardous chemicals, and specialized equipment . The chemobility . The bormobility . We inve2.−1 was observed that corresponds to the presence of a hydroxyl group (H2O and COOH possibly), O–H starching vibrations, and adoption of water molecules [−1 are attributed to the epoxide (C–O–C), carboxyl COOH/H2O), and ketone (C=O) groups, respectively [−1 contributed due to the absorption of water molecules, which is also attributed to the (C=C) aromatic vibration [The synthesis of GO and B-rGO was also tracked using FTIR spectra analysis, as shown in olecules ,31. The ectively ,33. Howeibration . −1 was assigned to the stretch vibration of C–O groups [−1. Therefore, the vibrational band 1735 cm−1 was assigned to the C=O functional group, which was slightly shifted to the 1695 cm−1 with lower intensity as compared with the GO spectrum. In the FTIR spectrum of B-rGO, the band around 1040 cm−1 ascribed to the asymmetric B–O–B stretch B-O bond among one tetrahedral and one trigonal B atom [−1, where the peak at 1180 cm−1 corresponded to the stretching vibration of the B–C bond. Particularly, the effective downshift in the C network was observed due to the B substitution, which was ascribed to the decreased force constant in the stretching vibration of the B–C bond in comparison with C–C, comparatively [Furthermore, the peak at 1043 cmO groups . Subsequl B atom . Usuallyratively . Howeverratively . −1 spectrum region. From the Raman spectra of GO, the intensity peaks found at 1349 cm−1 and 1601.17 cm−1 were ascribed to the D- and G- bands, respectively. The D-band at ~1349 cm−1 observed in the GO spectrum, was correlated to the defects and disorders in the graphitic lattice, due to the addition of oxygen-related functional groups. In addition, the second-order D, also known as 2D or G’, appeared at 2688 cm−1, attributing to the process of the two second-order phonon vibrations [D/IGI) defined the quality of the material and the relative concentration of sp3 defects in the sp2-hybridized graphene structure [D/IGI) ratio was also observed in the B-doped configurations, i.e., GO (0.94), B-rGO1 (1.094), B-rGO2 (1.12), and B-rGO3 (1.137). The increase in the D/IGI ratio after microwave-assisted hydrothermal treatment indicated the reduction of GO with the existence of boron atoms. The shift of the disorder and graphitic (G+D) peaks at 2934, 2933, and 2936 cm−1, respectively, indicated the existence of few-layer graphene [brations . After tbrations ,39. Howetructure . An incrgraphene . The shigraphene .2 domains. The electrical conductivity of GO was found to be further improved with boron doping, and this might have been dependent on the doping concertation of the incorporated atoms [Furthermore, the electrical conductivity measurement was carried out to integrate the Raman information. The electrical conductivity of GO and B-rGO samples was measured at room temperature using Hall-effect measurement (HMS-3000 Series) see . It was ed atoms . The inced atoms ,42.−1, respectively. Moreover, reduced O1s peak in the B-rGO survey indicated the reduction of oxygen-related groups in the GO-modified structure. The XPS survey scan for GO and B-rGO samples is shown in 2 bonded graphite carbon structure. It was also implied that the majority of carbon atoms were in honeycomb structure [4C (187 eV), BC2O2 (188 eV), BC2O (190 eV), and BCO2 (193 eV) peaks, confirming the successful doping of the GO carbon network with boron atoms [The deconvolution of the C1s spectra in the B-rGO indicated several peaks comprising of C=C (285 eV), C–OH (286 eV), and C=O (288 eV), related to the various chemical bonding carbon in the reduced graphene oxide structure. Especially, an intense peak in the C1s spectra at 284.75 eV corresponded to the C–C sptructure . Figure tructure , indicaton atoms . The B-son atoms . The XPSThe crystalline structure of GO and boron B-rGO has been investigated by the XRD diffraction pattern. θ, λ, n, and d are the scattering angle, the wavelength of the incident x-ray (1.54 Å), the order of reflection, and the interlayer distance, respectively. The interlayer distance of GO ~8.05 Å showed an agreement with reported work [Moreover, the interlayer distance between the wave field and the crystalline plane was determined by using Bragg’s Equation (1) ,(1)λ=2dted work ,52. Highted work .2 domains in the B-rGO. Moreover, the extra shoulder in the UV-Vis spectra observed from 375 nm to 386 nm for B-rGO samples correlated to the n to π* transitions C=O bonds [The optical bandgap of B-rGO samples was extracted using ultraviolet−visible (UV-Vis) absorption spectral analysis and the Tauc plots, as shown in =O bonds . This coThe optical bandgap sketched for GO, B-rGO1, B-rGO2, and B-rGO3 is shown in mR, as presented in mR was performed to ensure the maximum surface plasmon excitation. The optimal SPR response with the deepest curve was determined from the gold thin film with 50 nm thickness, as shown in The optical constant for the boron-doped reduced graphene thin film samples , particularly the real part of the dielectric constant and complex refractive index was determined by applying Equations (2)–(11) at 633 nm, as shown in dδ were investigated. Particularly, the high-performance SPR sensing layer was expected to possess low FWHM and high dδ values [dδ relative values calculated from Equation (19) for the gold, GO, thermally reduced GO, B-rGO1, B-rGO2, and B-rGO3 samples were found to be 359.64 nm, 103.82 nm, 100.57 nm, 128.85 nm, 128.16 nm, and 127.63 nm, respectively. The constant optical values of the B-rGO samples were decreased in comparison to that of GO and rGO, as shown in d values . Figure The measured thickness of the Au and B-rGO layers was found to be 50 ± 1.5 nm and 5± 1 nm, respectively. In 2SO4) (97%), phosphoric acid (H3PO4) (85%), potassium permanganate (KMnO4) (99.5%), hydrogen peroxide (H2O2) (30%), and other analytical grade reagents purchased from R&M, Selangor, Malaysia. Boric acid  was purchased from Sigma-Aldrich. Graphene oxide (GO) was synthesized by improved Hummer’s method [Graphite flakes (~50 μm), ethanol (95.0%), hydrochloric acid (HCl) (37%), sulfuric acid , which formed a dark green solution. The process was carried out in an ice bath to prevent overheating and explosion. The existing solution was stirred for 12 h to oxidize and exfoliate the graphite into a few layers of GO structure. After the completion of the reaction, H2O2 was added to stop the further reactions. At that point, the solution color was changed into a dark yellow-brown. Furthermore, 1 L of deionized (DI) water was used to dilute the solution, and then its pH level was adjusted ~1. The obtained mixture was then centrifuged at 5000 rpm to collect the graphite oxide and decant away the acid. The obtained oxidized graphite flake was further washed with the 10% HCl to remove the impurities like potassium and manganese ions, which are typically trapped in the solid. Afterward, the remaining mixture solution was washed numerous times with DI water while waiting for the pH level to reach ~1. GO flakes were then collected by a centrifugation process at 10,000 rpm. The GO flakes were dried in a Freeze Dryer and ground into a fine powder. At this stage, the powder was exfoliated into a few and single layers, so it was referred to as graphene oxide (GO) powder. Initially, 360 mL HThe GO solution (70 mg/100 mL) was prepared in DI water followed by continuous stirring for 2 h and sonication for 0.5 h .One to 3Morphology of the B-rGO, with energy dispersive X-ray (EDX) component mapping, was examined by field emission scanning electron microscopy . The functionalized surface of the GO and B-rGO thin film was studied by Fourier transform infrared (FTIR) spectroscopy . Raman spectroscopy  was also performed to reconfirm the arrangement of the composites. The imperfections and defects in the GO and B-rGO samples were also analyzed using Raman spectroscopy. In Raman spectra of GO and B-rGO, various peaks with different intensities appeared, where each peak to the material, followed the imprints and grouping of deformities in materials.−8 mbar through monochromatic Al Ka radiation (1486.6 eV). The XPS spectra were further analyzed with the help of the Origin  software. The deconvolution of multiple peaks was performed on XPS raw data. The existence of individual functional groups in XPS spectra was also analyzed from multiple peaks by the implication of Gaussian curve fittings, where the estimation of the baseline was performed by utilizing the adjacent-averaging technique. The electrical conductivity was measured at room temperature using a Hall Effect measurement .The optical characterization of spin-coated GO and B-rGO thin film was performed by UV-Vis Spectrophotometer  at room temperature. The thickness estimation was obtained from directly utilizing the surface harshness analyzer . The XRD estimation was also conducted for additional affirmation of crystallinity and synthesis of GO and B-rGO powder samples by utilizing XRD . The XRD analysis was performed over a 5–90° range with step size 0.01/s. Likewise, the existence of various functional groups was also confirmed through the support of X-ray photoelectron spectroscopy analysis . The XPS survey spectra were recorded from 0 to 1200 eV, under pressure conditions of 10The reduced optical bandgap energy of B-rGO indicates the prospective utilization of the material in optoelectronic device applications. The optical bandgap and optical constants of the B-rGO samples were obtained from the UV-Vis spectrum of a thin film. The GO and B-rGO dispersion solutions in N-Methyl-2-pyrrolidone (NMP) with a concentration of 0.25 mg/mL were used for the thin film deposition. The process was complemented by sonication or 0.5 h followed by the strong magnetic stirring for 2 h. Before spin coating, the obtained dispersed solution was centrifuged at 6,000 rpm to segregate the undissolved B-rGO particles. Later, B-rGO based thin film was prepared by using a spin coater (POLOSTM) at 3,000 rpm. From a theoretical perspective, the relationship among the parametric values obtained from UV-Vis spectroscopy, namely; absorption (A), transmission (T), and reflectance (R) could be defined by Equation (2) .(2)R+T+I(d) is the intensity at a depth of thickness d, oI is the intensity at zero thickness, and a is the absorption coefficient. The optical bandgap structure and the type of electronic transitions could be obtained from the absorption coefficient [gE) could be determined by using Equation (6).hv is the photon energy, gE is the energy bandgap; a is the absorption coefficient, and β is a constant for disorder parameter which is independent of photon energy. The value of parameter j denotes the nature of transition, where the parametric value of J, 1/2 used for direct allowed transitions, and 3/2 used for the direct forbidden transitions. However, the j parametric value of 2 is described for indirect allowed transitions, and 3 defines the indirect forbidden bandgap transitions [hv) verses (ahv)2. Furthermore, the imaginary part of the refractive, K (extinction coefficient) correlated with an absorption coefficient by the Equation (7).λ is the wavelength of the light wave. Based on the UV-Vis reflectivity measurement, the real part of the refractive index (n) could also be obtained from the Fresnel Equation (8) based on the reflectivity measurement using Equation (9).K, and n.rε and iε are the real and imaginary parts of the B-rGO dielectric constant, respectively.The Bear–Lambert law (Equation (3)) establishes the relationship between light attenuation through the specific material and its properties, where the relation between transmittance and absorbance of light could be defined . The trafficient . The optnsitions . The bornsitions . Therefon = 1.77861) was fixed on the rotation table and circled with a step size of 0.1° using a stepper motor . In this system, the He–Ne  laser beam was utilized with a photodiode detector. The surface plasmons resonance of the prepared samples was studied using our customized system, which was entirely based on the Kretschmann configuration, as shown in spK (surface plasmons vector) as shown in Equation (12).c is the velocity of light, ω is the frequency and The existence of resonating free electrons with the collective oscillation on the plasma surface  may induce charge density transverse waves propagation along the plasma surface. The oscillation of the transverse wave normal to the plasma surface is called surface plasmons. The surface plasmons resonance gets excited when the electromagnetic waves are coupled through the particular medium on the metallic surface. The light source must be P-polarized to the plasma surface, where the SPs only have the electric field component normal to the surface . Consequcθ), therefore cθ = sin−1(n2/n1). Likewise, the evanescent waves induced within the medium with a lower refractive index, the induced waves decay exponentially to the interface distance between both mediums. Therefore, the evanescent wave vector (Kevan. ‖) can be determined by Equation (15).θ, n1, and λ are the incident angle, the refractive index of gold, and the wavelength of the incident light, respectively. When the evanescent wave excites the surface plasmons, the intensity of reflected light decreases sharply. The decrease in excited plasmons induces the energy conversion to photons and phonons. Therefore, the SPK should be equal to evan.‖K. According to the requirement of the phase-matching condition for SPR excitations [SPRθ angle as a function of related refractive index could be obtained by solving Equations (14)–(16) together (Equation (17)).Furthermore, the total internal reflection (TIR) occurs when the light waves travel from a material with a higher refractive index to another material with a lower refractive index. For TIR, the incident angle (θ) must be greater than the critical angle  were also considered as an essential parameter, which describes the length over which the surface plasmon was sensitive to the changes in the refractive index in the dielectric medium. It could be calculated using Equation (19).0λ is the free space wavelength, mε, and dε are the real part dielectric constants of gold and the adjacent material to the gold, correspondingly [Specifically, the SPR angle of the incident P-polarized light mainly depends on The gold-coated glass  with a uniform thickness of 50 nm Au layer was purchased from Platypus Technology, USA. The thickness of the Au layer was further confirmed by the surface roughness tester . The B-rGO dispersion solution (0.25 mg/mL) in NMP was attained after the 1 h sonication process, using the probe sonicator. After that, the unexploited flakes of B-rGO were removed by the centrifuge process at 6000 rpm for 10 minutes. The Au-coated glass was washed with DI water before the deposition of the B-rGO layer. The uniform B-rGO thin film was attained by using a spin-coating technique at the rotation speed of 4,500 rpm followed by its thickness measurement using the surface roughness tester. Later, the sensing layer coated on top of the gold film was attached to the SF11 prism using the Norland index matching liquid, Newport to prepare the sensor chip.In this work, we studied the enhanced SPR response with a tunable optical bandgap in the visible region of B-rGO. The B-rGO was synthesized using a customized microwave-assisted hydrothermal approach. The successful synthesis of B-rGO was confirmed by standard FESEM, FTIR, RAMAN, XRD, and XPS-based analyses. The optical bandgap and optical constants for the B-rGO were extracted from the UV-Vis absorption spectrum. The direct bandgap for the three different B-rGO samples was found to be ~2.91, 2.94, and 3.05 eV, whereas the optical bandgap for GO was found to be 3.41 eV. Interestingly, the enhanced P-type electrical conductivity with reduced optical bandgap was also observed. The surface plasmon resonance-based sensing response of the samples was investigated theoretically as well as experimentally using the customized Kretschmann configuration and found to be enhanced for B-rGO. The acquired results validate the tunability of the optical bandgap and the enhanced surface plasmons resonance in B-rGO. The comparative depth penetration response obtained for B-rGO samples, predicts its utilization in future highly sensitive SPR-based sensors. The tunable optical and electronic properties of B-rGO could be further optimized for optoelectronic, sensor, and light-harvesting applications.


Polytriazole polyethylene oxide-tetrahydrofuran (PTPET) elastomer was prepared by N100-g-GAP and alkynyl terminated polyethylene oxide-tetrahydrofuran (ATPET). The resulting PTPET elastomer was fully characterized by TGA, DMA, FTIR and mechanical test. The above analysis indicates that PTPET elastomers using N100-g-GAP as curing reagent have the potential for use in propellants. The overall formulation test of the composite propellants shows that this curing system can effectively enhance mechanical strength and bring a significant improvement in the interface interaction between the RDX & AP particles and binder matrix.A new energetic curing reagent, Glycidyl azide polymer grafted tetrafunctional isocyanate (N100- Glycidyl azide polymer (GAP) is generally used as the energetic binder in solid composite propellants with a variety of oxidizers, such as ADN, RDX, CL-20, and AP. N100  is a classic polyfunctional isocyanate curing reagent. The combination of GAP and N100 is a general cross-linked polyurethanes approach used in solid composite propellants ,4,5,6,7.Using alkynyl terminated polyethylene oxide-tetrahydrofuran (ATPET) as a binder, GAP as a curing reagent is an effective method to solve that problem . HoweverGraft polymer refers to the product formed by chemical bonds on the macromolecular chain with appropriate branched or functional side groups. The combination of the properties from the main chain and the branch chain contributes to the overall performance. By grafting, two polymers with distinct properties can be bonded together to form a graft with special properties. Therefore, the graft modification of polymers has become a simple and effective method to extend the application field of polymers and improve the properties of polymer materials.g-GAP, the purpose of finding a graft copolymer as a curing reagent can be achieved, and the strength of the elastomer cross-linked network might be enhanced. At the same time, the functional group between unreacted hydroxyl groups and ammonium perchlorate as well as RDX can form a hydrogen bond. This graft polymer can act as a bonding reagent to reduce the dehumidification behavior of solid particles.This study aims to design an azide curing reagent with a bonding effect that can be applied to the click chemistry, by combing the curing and bonding functions. By reaction between GAP and N100 to form a graft copolymer named N100-Mn = 743 g/mol, f = 4.05) and two kinds of GAP (Mn = 1000 g/mol and Mn = 4000 g/mol) were purchased from Liming Research & Design Institution of Chemistry . The alkynyl-terminated polyethylene oxide-tetrahydrofuran  sample was received from the Beijing Institute of Technology Flame Retardant Technology Co., Ltd. . Aluminum powders (Al), hexogen (RDX), A3 (BDNPA/BDNPF) and ammonium perchlorate (AP) were purchased from Xi’an North Hui’an Chemical Industries Co., Ltd. . All the above reagents were vacuum dried at 50 °C before use. Other reagents were purchased from Beijing Tongguang Reagent Co., Ltd.  and used directly without further treatment.N100  was placed in a three-necked flask with a mechanical stirrer (500 r/min), and the temperature was slowly raised to 80 °C. N100  was slowly added into the flask through a funnel. And three drops of trimethylamine (TEA) were added as a catalyst. The mixture was stirred at 90 °C for 21 h. The TEA was removed by vacuum distillation. An orange viscous liquid N100-g-GAP was obtained after vacuum drying at 50 °C in a yield of 96%.GAP (g-GAP and GAP (Mn = 4000 g/mol) with ATPET by the same functional group ratio of azide to alkyne. The PTPET was cured into an elastomer that was 15 cm long, 6 cm wide, and 4 mm thick at 50 °C for seven days. The synthetic route of the N100-g-GAP and PTPET elastomer is illustrated in g-GAP in The PTPET elastomers were obtained by curing N100-g-GAP was further applied to the PTPET composite propellants (consisting of RDX/AP/Al/A3/ATPET/N100-g-GAP). The above propellants had 76 wt% total solid content , A3 plasticizer 12 wt% and 12 wt% ATPET-GAP binder system. After kneading and casting, the propellants slurry was cured at 50 °C for 7 d. The propellant’s were cut into dumb-bells of pieces based on GB/T 528, and the experimental analysis was carried out using a universal tensile machine.The prepared N100-2O3 crucible, Germany) instrument with the following test condition: test atmosphere of N2, the scanning rate of 10 °C/min and the temperature range of 40~500 °C. The microscopic interface properties of the propellant’s samples were researched by scanning electron microscopy .FT-IR spectra were recorded on a Nicolet AVATAR 6700 spectrometer . The molecular weight and distribution were tested by gel permeation chromatography . The mechanical properties of the samples were measured on a tension test . Dynamic mechanical measurements (DMA) experiments were proceeded using a DMA/SDTA 861 equipped (−90~60 °C) with a cup fixture of 1 Hz and a heating constant rate of 2 °C/min. Thermogravimetry analysis (TGA) was obtained by a Netzsch 209 F1  of the reaction product N100-g-GAP increases with the rise of the reaction time, and the curves become stable at 21 h. Comparing the outflow time of curves shifts to the left with time means that the molecular weight of the product N100-g-GAP is gradually increasing. It is clear that the polymer dispersity index (PDI) of the product N100-g-GAP is gradually broadened. H-NMR data of N100-g-GAP are listed in The GPC curves of N100-g-GAP change in reaction time as shown in Mn = 1000 g/mol) is at 3641 cm−1. It can be seen from the dynamic curve that this peak gradually becomes smaller as the degree of reaction increases, indicating that the hydroxyl group in GAP is gradually consumed in the reaction with -NCO. The peak at 3336 cm−1 belongs to the NH symmetric stretch, which is increasing with time. The asymmetric stretching vibration absorption peak in -NCO is at 2270 cm−1 and the stretching vibration of urea bond in C = O in -NCO is at 1681 cm−1. That is the typical characteristic peak of -NCO and its intensity decreases significantly as time passes. The peak at 770 cm−1 is attributed to the bending vibration peak in the carbamate formed by the reaction. Peak groups at 1722, 1533, and 1310 cm−1 are the stretching vibrational peak of the first, second and third zones in the formed amide. Most -NCO groups react with -OH to form carbamates, which can form hydrogen bonds with -NCO, -OH, etc., and have bonding effects. The above data confirmed that the copolymer N100-g-GAP has been successfully synthesized.The IR curves of N100-g-GAP) curve is weaker than that of PTPET (GAP) caused by grafting N100 which reduces the density of azide groups in the molecule. The 5%T temperature of both curves is around 250 °C, but the maxT temperature of PTPET (N100-g-GAP) is 10 °C lower than that of PTPET (GAP). However, this decomposition temperature has already allowed for practical use as it is over 400 °C.It is necessary to understand the thermal property of the PTPET elastomer which is an important parameter to consider the possibility for applications. TG-DTG data of the PTPET elastomers are summarized in tan δ) of the PTPET elastomers prepared by N100-g-GAP and GAP (Mn = 4000 g/mol), measured by the DMA, are shown in g-GAP) shows a slightly higher gT than PTPET (GAP). This phenomenon is supposedly due to the dense cross-linked network formed in PTPET (N100-g-GAP), which hinders the movement of the segment and increases the glass transition temperature. The cross-linked density of the PTPET will be confirmed in the swelling analysis in the next section. There is also a peak at −39.68 °C of the PTPET (GAP) curve due to the suspension GAP chain portion of the cross-linked network. The large molecular weight of the linear GAP becomes a longer segment after it formed in PTPET elastomer, and it shows β relaxation in DMA analysis. While there is no obvious β glass transition peak in PTPET elastomer prepared by N100-g-GAP. The length of the GAP segment is shortly after it is grafted onto N100, which is not enough to highlight the relaxation peak of its own segment.The loss factors (g-GAP and GAP (Mn = 4000 g/mol) were swollen in toluene at 25 °C. The swelling characteristics of samples were calculated according to the equilibrium swelling method [g-GAP and GAP are displayed in cM) and the volume swelling ratio (vq) curves, respectively. The calculated parameter results appear in g-GAP) showed a lower vq than PTPET (GAP). The cross-linked linking average molecular weight of PTPET (N100-g-GAP) was about 3510, which was lower than PTPET (GAP) with about 7405. The above results indicate that the cross-linking network of PTPET prepared by N100-g-GAP was denser and that more cross-linked points were formed [Prepared PTPET samples by N100-g method ,19,20. Te formed .g-GAP) elastomer had a better ability in stress than PTPET (GAP) elastomer, while the strain performance was reduced. The tensile experiment analysis explained that N100-g-GAP had a better ability in generating a cross-linked network than GAP in prepared the PTPET elastomer. Moreover, calculated parameters data from swelling analysis confirmed tensile experiment results.The previous study shows the addition of a cross-linked network in the polymer structure can improve its strength due to the increase of cross-linked density . The teng-GAP) elastomers, IR analysis was further carried out. The IR result of the carbonyl group is shown in g-GAP), it is clear that the free carbonyl locates at 1725 cm−1. While for the peak of double-associated hydrogen bond urea carbonyl and mono-association hydrogen bond urea carbonyl were found at 1640 cm−1 and 1685 cm−1, respectively.Hydrogen bonds between the molecular chains exhibit a strong bonding force at low temperatures . In ordeg-GAP and GAP were presented in 5%T) of the propellants prepared by GAP was at 204.9 °C, slightly lower than that of the N100-g-GAP at 206.7 °C. There were two main max decomposition peaks (maxT at 228.67 °C and 308.67 °C) in the propellants prepared by N100-g-GAP during the DTG curve from maxT of the propellants prepared by N100-g-GAP was slightly lower than GAP (231.78 °C). The TG-DTG curves indicated that there were two loss-wt% stages for propellants (N100-g-GAP), and that the 84.13% loss-wt% was resulted from the main breakage of the polyether backbone, while the 3.48 wt% was caused by the carbamate and part of the hard segment molecular chain. For the propellants (GAP), there is only one loss-wt% which was 84.70% that mainly due to the decomposition of the polyether polytriazole chain. Meanwhile, N100-g-GAP can replace the GAP to decrease the residual carbon by 4 wt% in propellants.The TG-DTG curves of the propellants prepared by N100-tan δ) was plotted as a function of temperature for different propellant samples. Propellants made by PTPET (GAP) and PTPET (N100-g-GAP) samples had measured gT temperature around −60.35 °C and −58.91 °C, respectively. That result was consistent with the swelling analysis that the high cross-linked density causes an increase in gT temperature of samples. The half-peak width of the tan δ curve of the propellants (PTPET (N100-g-GAP)) is broad, indicating that the cross-linked density of this propellant is higher than the propellants (PTPET (GAP)). The molecular weight distribution of the formed (PTPET (N100-g-GAP)) elastomer is wider than PTPET (GAP) in the composite solid propellant. The results obtained by DMA analysis are consistent with the previous GPC results. The analysis of interfacial interaction between solid particles and the PTPET elastomer matrix can be evaluated through DMA. It is clear that the damping coefficient can reflect the elastic response of the material and the dissipating energy losses. Decreased damping is evidence of improved interactions between solid filler and binder [g-GAP)) shows a noticeable decrease compared with the propellants (PTPET (GAP)), clearly manifesting that N100-g-GAP raises adhesion of the PTPET (N100-g-GAP) binder and solid filler.As shown in d binder ,26. The g-GAP would influence the composite propellants. A four-component propellant formulation containing RDX, AP, Al, and binder was selected to test, and the results were listed on the following g-GAP can significantly improve the tensile strength of the composite propellants at 20 °C. At the same time, it can confirm that the elongation at break loss of the propellants was small, while the elongation at breaking was somewhat lowered. The comprehensive analysis showed that the mechanical strength of the propellants prepared by N100-g-GAP was higher than GAP, indicating that the cross-linked density of the prepared elastomer was higher, which was consistent with the results of the above swelling and DMA analysis. The mechanical strength advantage indicating that this may be due to the formation of hydrogen bonds between the PTPET (N100-g-GAP) and the solid filler in the composite solid propellant.The mechanical test is an effective approach to testify how incorporation of N100-g-GAP-affects the interface effect of solid particles in composite propellants, a scanning electron microscope (SEM) was utilized to study the different samples by microscopy. g-GAP (g-GAP) elastomer between RDX and AP. The amino group on the carbamate can form a hydrogen bond with the N atom on the RDX and AP particles and acts as a bonding agent. The interface between N100-g-GAP, GAP and aluminum powder is not a good result. The above shows that N100-g-GAP can act as a binding reagent for RDX and AP propellants.In order to further access how N100-y. g-GAP A,B, and y. g-GAP C,D afterg-GAP with a higher crosslink effect for the PTPET system was successfully synthesized in this paper. Meanwhile, the urethane group formed in N100-g-GAP can form a hydrogen bond and has a bonding effect. Compared with GAP analysis, the PTPET elastomer prepared by N100-g-GAP has a higher crosslink density and thermodynamic stability. The use of N100-g-GAP significantly enhances the tensile strength of composite propellants at 20 °C. DMA and SEM analysis of propellant samples indicates an improved binder-filler interfacial interaction in the propellant composites containing N100-g-GAP.A new curing reagent N100-